1. Why tilt-to-change items like placemats and cards are often called holograms but are not
Some items, like placemats, stickers, and trading cards, appear to change or move when you tilt them. These are often called "holograms," but they actually work through a different mechanism [1]. Holograms use a phenomenon called "interference," where laser light is overlapped to record a 3D image. In contrast, these sheets use "refraction," where small lenses on the surface bend light to show different pictures from different angles [1]. Even though both look three-dimensional and dynamic, the physical phenomena behind them are entirely different.
2. The surface of a lenticular sheet is made of rows of small convex lenses
If you magnify the surface of this sheet, you see small convex lenses shaped like kamaboko (fish cakes) lined up densely with no gaps [1]. Each individual lens acts as a device that shows different pictures depending on the viewing angle. On the printed surface underneath the lenses, multiple images are cut into thin, vertical strips and arranged alternately [1]. It helps to imagine this as taking many photos, cutting them into small pieces, shuffling them, and then arranging them in a strict pattern.
3. Why a lenticular picture changes when you change your viewing angle
When you gently move a magnifying glass over paper, the area that looks large moves. Lenticular lenses do something very similar [1]. As your viewing angle changes, the position of the vertical strips that each lens magnifies shifts. This brings different strips into your field of view than before, which makes the picture appear to change or move [1].
4. Two lenticular effects: changing pictures and popping-out pictures
Lenticular effects are broadly divided into two types [2]. The first is the "changing" effect, where the picture suddenly switches or appears to move like a flipbook depending on the angle. The second is the "3D" effect, where slightly different images are delivered to the left and right eyes, making the picture appear to pop out without special glasses [2].
5. What "lpi" means: how many lenses fit within 1 inch
The fineness of the lenses is measured in a unit called "lpi," which indicates how many lenses fit within 1 inch (about 2.54 cm) [3]. Commercially available sheets range from about 18 lpi to 150 lpi, with higher numbers meaning finer lenses. For example, a 150 lpi sheet, often used for small postcards, has 150 lenses per inch. The width of each lens is about 0.17 mm (calculated as 2.54 cm divided by 150), and the entire sheet is only 0.26 mm thick [3]. This is much thinner than a 1-yen coin, which is about 1.5 mm thick.
6. The oldest known lenticular patent, filed by John Jacobson in 1898
The oldest known patent related to lenticular technology was filed by John Jacobson in the US in 1898 and granted in 1899 [2]. It described a technique of covering photos with a transparent base that had grooves carved into the surface. Later, in 1912, Walter Rudolf Hess filed a patent in the US for a celluloid film with cylindrical lenses lined up. In the same year, Louis Cheron filed a patent for a similar mechanism in France [2]. This means similar inventions were born in different countries at almost the same time.
7. How lenticular technology spread to badges, Vari-Vue items, and candy premiums
In 1952, Victor Anderson and his company filed a patent for a method of assembling display items where pictures switch using this technology. Records indicate their first product was a small badge that said "I Like Ike" [2]. In 1953, the trademark "Vari-Vue," which became a representative brand for lenticular products, was registered [2]. From the 1950s to the 70s, many cards that changed pictures when tilted were made as premiums for American candy "Cracker Jack" and cereal "Cheerios." Around 1966, postcards featuring images like a winking woman began to be sold by multiple manufacturers [2]. During the 1950s to 70s, Vari-Vue supplied changing cards as premiums for Cracker Jack, and lenticular premiums were also used with Cheerios in the 1950s.
8. How the winking lenticular stickers on the "Dakko-chan" doll became a hit in Japan
In Japan in 1960, a doll called "Dakko-chan" became an unprecedented hit. It is said that lenticular stickers that appeared to wink depending on the viewing angle were used for the doll's eyes [4]. The toy manufacturer Tsukudaya also sold these wink stickers separately on October 12, 1960. They were sold as a set of three eyes and glue for 80 yen [5]. The popularity of the doll itself had been rising since around June of that year.
9. The parallax barrier method, a similar lens-free 3D technology, and lenticular uses today
There is another method for seeing 3D images without glasses that does not use lenses. This is called the "parallax barrier" method, which involves creating a grid of narrow gaps in a transparent plate [6]. Nintendo's handheld game console, the Nintendo 3DS, achieves naked-eye 3D viewing using the parallax barrier method, not lenticular lenses [6]. The visual effect is similar, but the mechanism is different. Additionally, the goggle-style computer "Apple Vision Pro," released in 2024, uses lenticular lenses. The outer screen has three layers, one of which is a lenticular layer that makes the eyes of the person inside appear 3D from the outside [7]. The same mechanism used in 1950s candy premiums is still alive in the latest devices.
10. How to observe the lenses of a lenticular item at home
If you have a sticker, card, or placemat at home that changes when tilted, try slowly tilting it and holding it up to the light to observe the arrangement of the lenses inside. You might realize that what you thought was a hologram is actually refraction by lenses. When you do this, also try to distinguish whether it is a "changing" type where the picture switches, or a "3D" type where it pops out. If you want to know more about the mechanism, the explanations from Marubi [1] and Kayo Printing [3] are good clues. Marubi’s explanation details the lens structure and image mechanism, while Kayo Printing introduces the types of commercially available lenses and their thickness.